DiskScan is a tool to scan a block device and check if there are
unreadable sectors, in addition it uses read latency times as an
assessment for a near failure as sectors that are problematic to read
usually entail many retries.

Diskscan will only perform reads in its disk surface scan so it is
not destructive in any way and it will report on all the key metrics
needed to decide if the disk is good or not.
